Before President Obama took office, the U.S. had 25 gigawatts of wind power, and the government’s “base case” energy forecast expected 40 GW by 2030. Well, it’s not quite 2030 yet, but we’ve already got 50 GW of wind. We’ve also got about 5 GW of solar, which isn’t much but is over six times as much as we had before Obama. Mitt Romney has suggested that wind and solar are “imaginary” sources of energy, but they can now power 15 million homes, and their industries employ more than 300,000 Americans. That’s real.

On Thursday, Obama was in Colorado, a big wind state, talking about wind. On Wednesday, Romney was in Iowa, another big wind state, not talking about wind. But the media, for a change, were talking about wind, because Republicans in Iowa have criticized Romney’s opposition to offering tax credits for the wind industry. I would also point out, and not only because The New New Deal is coming out next week, that Romney and his party opposed the Obama stimulus bill that revived the wind industry and the rest of the clean-tech sector from a near death experience. As I’ve written before, wind turbines the size of 747s were rusting in the fields after the financial collapse of 2008; after Obama signed the stimulus, wind companies began pouring billions of dollars back into the U.S.

Anyway, it’s nice to see political reporters paying attention to something that matters. Romney would say the tax-credit issue goes to Obama’s penchant for supporting goodies for specific industries, which isn’t really fair, since as Obama often says but reporters rarely repeat, Romney and his party support outrageous subsidies and tax breaks for the spectacularly wealthy oil industry. But it’s true that Obama has tried to support clean energy in general, and the results have been remarkable.

For example, the generation of renewable electricity has doubled on Obama’s watch. The stimulus has financed the world’s largest wind farm, a half-dozen of the world’s largest solar farms, the nation’s first refineries for advanced biofuels, a new battery industry for electric vehicles, unprecedented investments in cleaner coal and a smarter electric grid and over 15,000 additional clean-energy projects. The Obama Administration has also approved the first 17 utility-scale solar projects on public lands, as well as historic new fuel-efficiency and appliance-efficiency standards that will dramatically reduce our energy consumption. Last year, the U.S. was the least dependent on foreign oil it’s been since 1995, and our greenhouse-gas emissions are dropping even though the economy is growing.

But you don’t hear about that much. Even after the Massey coal-mine collapse, the BP oil spills, the Fukushima nuclear meltdown and now the Chevron refinery fire, there hasn’t been a great debate about clean energy and Obama’s green revolution. (Wind and solar spills are a problem only when you don’t have a sweater or sunscreen.) Instead, as I wrote in a magazine column this week, we’ve been mired in a fake debate over Solyndra. The tax credit for the wind industry is as good a place as any to start a real debate, not just because it creates jobs in Colorado and Iowa — industry-targeted tax credits always create jobs in the industries they target — but also because it exploits an inexhaustible domestic source of electricity that doesn’t broil the planet.

Wind and solar essentially were imaginary before Obama took office, but now they’re a real threat to the fossil-fuel status quo. That’s why their tax credits, which used to be renewed routinely with overwhelming bipartisan support, have become so controversial and why Romney would risk alienating voters in windy swing states to oppose it. Ultimately, the argument over wind and other clean energy, like so many arguments in this campaign, is an argument about change.